Reversible bipolar thermopower of ionic thermoelectric polymer composite for cyclic energy generation

The giant thermopower of ionic thermoelectric materials has attracted great attention for waste-heat recovery technologies. However, generating cyclic power by ionic thermoelectric modules remains challenging, since the ions cannot travel across the electrode interface. Here, we reported a reversible bipolar thermopower (+20.2 mV K−1 to −10.2 mV K−1) of the same composite by manipulating the interactions of ions and electrodes. Meanwhile, a promising ionic thermoelectric generator was proposed to achieve cyclic power generation under a constant heat course only by switching the external electrodes that can effectively realize the alternating dominated thermodiffusion of cations and anions. It eliminates the necessity to change the thermal contact between material and heat, nor does it require re-establish the temperature differences, which can favor improving the efficiency of the ionic thermoelectrics. Furthermore, the developed micro-thermal sensors demonstrated high sensitivity and responsivity in light detecting, presenting innovative impacts on exploring next-generation ionic thermoelectric devices.

1) For applications the most important aspect is change of S after switching from one electrode to another, as illustrated by regions I-IV in Fig S6 of the supplemental material. The switching process is shown schematically in fig. 4a.
In the introduction (p 3) the authors say that "... it is impossible to repeatedly turn on/off the heat in the real industry..." It is not obvious to me why it would be easier to change electrodes. Perhaps the authors could try to expand on their argument.
2) If I am not mistaken the authors observe S = 20 mV/K when using Cu electrodes, and S = -10 mV/K for CNT electrodes. This finding cannot be explained in terms of ionic heats of transport Q+ and Q-, since the latter are material properties, which by definition are independent of the electrodes. The MD simulations suggest that the electrodes modify the ionic probability distribution in a nanoscale surface layer. Since this is the main finding of their paper, the authors should try to explain or at least better characterize experimentally this effect.
3) I feel there is a misunderstanding concerning eq. (1) and the subsequent discussion. In fact, eq. (1) does not give the stationary Seebeck coefficient of iTE materials, but rather the transient ion current after switching on the temperature gradient.
Thus eq. (1) would explain the initial slope of the cusps occuring in Fig. 1 d,e after each change of Delta T. Perhaps the authors find it helpful to have a look at ref. 18 or at a paper by Janssen and Bier (Phys. Rev. E 99, 2019).
Reviewer #3 (Remarks to the Author): The author used the interaction between ions and electrodes to control the migration of cations and anions by changing the electrode materials, and achieved positive and negative conversion of the thermopower of PNP films. This reversible p-n transition provides a new approach for the construction of thermodiffusion ionic thermoelectric devices. However, this work is incomplete, and there are many issues which should be further clarified. I also have some suggestions for the authors to further polish their paper.
1. The title of this paper says "ionic thermoelectric polymer composite for continuous energy generation", however, the work on ionic thermoelectric generator is not yet complete. The low power generation of a single PNP film is not meaningful to evaluate its performance. The author needs to connect multiple PNPs in series and consider its stability after many cycles.
2. According to Fig. 4, it needs switching the electrodes while also disconnecting the external load and waiting for a certain period to generate the open circuit voltage. I think the generator does not produce power continuously, which is not consistent with the "continuous power generation" claimed in the title of this paper. In addition, there is an error in the labeling sequence of Fig. 4b. 3. For the measurement of the Seebeck coefficient, the connection between the positive and negative poles of the voltmeter and the hot and cold ends of materials will affect the positive and negative values of voltages. Therefore, please supply the measurement details, schematic and physical diagram of measurement equipment for the Seebeck coefficient. Moreover, in Fig. 1d, the relationship between the thermoelectric voltage and temperature difference of p-type Cu|PNP|Cu does not correspond to Fig. S2. The same problem exists in Fig. 1e. 4. What are the advantages of VA-CNT as electrodes compared to other carbon materials such as SWCNT or MWCNT? The reason for choosing VA-CNT arrays as electrodes should be described.
5. There is an error in the figure caption of Fig. 2a and Fig. 2b, which is inconsistent with the description in line 185 on page 10.
6. The ionic thermoelectric polymer was described as all-solid-state i-TE material. However, this i-TE material contains liquid propylene carbonate (PC), so it is not considered to be an all-solid material.
The results presented in this manuscript are interesting. However, some issues should be understood better.
(1) As Cu is an active metal, the authors should check whether there is any reaction at the interface between the polymer composite and the Cu electrodes.
Response: As the reviewer suggested, we further conducted to study on the stability of Cu electrodes when contacting the polymer composite during the thermopower measurement. In this work, the Cu electrodes used for the test are conductive copper tapes. Firstly, we checked the surface color of the Cu electrodes before and after the thermopower measurement, and don't observe any color change on the surface of the used Cu electrodes. We further performed the X-ray photoelectron spectroscopy (XPS) measurement to characterize the chemical state of the surface of the unused Cu 2 electrode and the used Cu electrode after the thermopower testing of the PNP composite.
As shown in Fig. R1a, the XPS curves of the unused Cu and the used Cu electrodes overlapped well and no new peaks were observed on the used Cu electrodes, which suggests that there is no chemical reaction on the Cu electrode during the test. Moreover, we also investigated the cycle stability of the PNP i-TE polymer materials using the Cu electrodes. As shown in Fig. R1b, there is no obvious decay of the produced thermoelectric voltage of the Cu|PNP|Cu system after 30 cycles test. Thus, the above test results represented the high stability of the Cu electrodes with the PNP composite.
In addition, the Cu electrode is also widely used to work as a test electrode when measuring the ionic Seebeck coefficient of polymer composite in some recent work (Adv. Energy Mater. 2019, 9, 1901085).
We have added the discussion of the stability of Cu electrodes in the revised manuscripts (Page #6, Line 115) and Supplementary Information (Page #7, Fig. S4). (2) The authors should carry out control experiments by using stable metals like Au or Pt as the electrodes.
Response: As the reviewer suggested, we conducted the control experiment using stable metals, Pt and Au as the electrodes. To keep consistent, the thermopower measurement setups of the Pt|PNP|Pt and Au|PNP|Au systems are the same as the From the test results, both Pt|PNP|Pt and Au|PNP|Au systems also exhibited typical ptype characteristics, which is consistent with the value of thermopower (~20 mV K -1 ) measured by the Cu electrodes.
We have added the discussion of the control experiments by using stable metals, Au and Pt, as the electrodes to the revised manuscript (Page #6, Line 121) and Supplementary Information (Fig. S3).
(3) As the authors mentioned, the interaction between the CNT electrodes and the polymer composites can greatly affect the thermovoltage. Details should be provided on the fabrication of VA CNTs, the structure like the length and diameter and properties like the conductivity of the VA CNTs, and the fabrication procedure of the CNT electrodes.
Response: As suggested by the reviewer, we further introduce the properties of the CNT electrodes. The aligned CNT films were purchased from Nanjing Ji Cang Nano Technology Co., Ltd. (Nanjing, China), and the product number is JCNTF-20C, which is a kind of CNT-based thin film. As provided by the vendor, the aligned CNT film was fabricated by the chemical vapor deposition (CVD) method and continuously grown into a large-scale thin film of about 100×150 cm and has a very thin thickness of about ~10 &m, as shown in Fig. R3a. The surface morphology of aligned CNTs was also characterized by SEM and TEM. As shown in Fig. R3b, the aligned CNT consists of bundles of carbon tubes which were mainly aligned in the length direction of the film with small entanglements. This aligned-CNT exhibits high conductivity of 3×10 5 S m -1 , low sheet resistance of 1~1.5 $ m -2 , high mechanical strength of ~120 MPa, high stability and flexibility, low cost, and self-adhesive nature.
As the reviewer suggested, the detail of the properties of the aligned CNTs has been updated in the revised manuscript (Page #7, Line 143) and Supplementary   (4) The contact area between the CNT electrodes and the polymer composites can affect their interaction and thus the thermovoltage. The authors should study the effect of the contact area on the thermovoltage, such as using VA CNTs of different heights along the vertical direction.
Response: Yes, we think the name of the vertical-aligned CNTs may lead to misunderstanding for the reviewer. In this work, the "aligned CNT" is a kind of carbon nanotube thin film with an average thickness of ~10 &m, which is made of bundles of carbon tubes arranged uniformly in the length direction ( Fig. R3b). When testing the thermopower, the aligned CNT films were placed horizontally, and the length direction of the aligned CNT was parallel to the i-TE polymer material, which is not vertical to the polymer material. As the a-CNT film is very thin and easy to bend when vertically placed, it is not suitable for testing thermopower by placing this a-CNT vertically to the PNP i-TE materials. To avoid misunderstanding, we have changed the name "vertical aligned CNT" to "aligned CNT (a-CNT)" in the revised manuscripts.  The fitting curves -#V vs #T of the PNP with a-CNT and a-CNT-B (another vendor) electrodes. 7 (5) Can the n-type behaviour be observed by using single-walled CNTs or multi-walled CNTs commercially available?
Response: Yes, the n-type behavior is also observed by using single-walled CNTs or multi-walled CNTs as the test electrodes. As the reviewer suggested, we also conducted to measure the thermopower of PNP using the single-walled CNTs (SWCNTs) and the length direction with small entanglements, a-CNT films exhibited higher conductivity of 3×10 5 S m -1 , a lower sheet resistance of 1~1.5 $ m -2 , excellent flexibility, higher mechanical strength of ~120 MPa and low cost compared to common SWCNT and MWCNT films, as summarized in Table R1.
We have added the thermopower performance of the SWCNT and MWCNT electrodes in the revised manuscript (Page #7, Line139, Figs. 1d-e) marked with red color and Supplementary Information (Page #S8, Fig. S5 and Page #S25, Table S1).  Response: As the reviewer suggested, we further tested the thermopower of Cu|PNP|Cu, and a-CNT|PNP|a-CNT systems by introducing temperatures in both positive and negative temperature gradients (±#T1) (i.e., +6K, -6K, +5K, -5k… and ±1K). The remeasured generated voltage (V1) of the Cu|PNP|Cu system under different #T1 is shown in Fig. R6a, which exhibited a typical thermoelectric behavior. As shown in Fig. R6c, the slope of the fitting curve of re-measured -#V1 (Vhot-Vcold) vs #T1 is close to the previous data acquired under positive temperature gradients (-#V2 vs #T2) in the first submitted manuscript. According to Eq. R1, the re-measured thermopower of Cu|PNP|Cu is about 20.2±4 mV K -1 , which is consistent with the previously measured results (~20 mV K -1 ), as shown in Fig (7) Understand that the samples were prepared and they were tested in inert environment. Does the humidity affect the thermovoltages using VA-CNTs or Cu as the 11 electrodes, because humidity usually affect the ionic thermovoltage.
Response: According to the reviewer's suggestion, the thermopowers of the PNP samples using Cu, and a-CNT electrodes at different relative humidity (50% RH~90% RH) were further investigated. The curves of the produced thermal voltage of Cu|PNP|Cu sample at 90% RH was shown in Fig  Meanwhile, the i-TE performance of the n-type CNT|PNP|CNT system was also investigated under different humidity. The measured thermal voltage of the a-CNT|PNP|a-CNT sample under different #T at RH 70% is shown in Fig. R8a. The ionic thermopower of the n-type a-CNT|PNP|a-CNT sample slightly increased from -8.11±1.5 mV K -1 at RH 50% to -9.3±0.7 mV K -1 at RH 60% and reached the maximum value of -10.2±0.83 mV K -1 at RH 70%, which was caused by water absorption effect as discussed above. Further increasing the humidity level, the thermopower reached a relative saturation value of -9.7±0.86 mV K -1 at RH 80% (Figs. R8b-c).
In summary, increasing the humidity level generally enlarged the magnitude of the thermopower of p-type Cu|PNP|Cu and n-type CNT|PNP|CNT, but it does not influence the sign of the p-type characteristic of the Cu|PNP|Cu and the n-type behavior with a-  This is an interesting paper on ionic thermoelectric materials and devices. As their main result the authors present a novel technique of transforming waste heat to electric energy. In previous work this was achieved by perioidically disconnecting the iTE material from the heat source, the present work realizes a cyclic thermopotential by periodically connecting two types of electrodes. As their essential feature, these electrodes modify the TE response and in particular the sign of the Seebeck coefficient. Though this is possibly a very interesting paper I do not recomment publication in its present form. Several points need to be 14 clarified: (1) For applications the most important aspect is change of S after switching from one electrode to another, as illustrated by regions I-IV in Fig S6 of  is not necessary to change the thermal contact between the material and heat source, and thus don't need to re-establish the temperature difference either, which can favor improving the efficiency. In addition, to better demonstrate the advantages of the interesting properties, we further optimized the structure of the ionic thermoelectric generator (i-TEG) module. As shown in Fig. R9, the i-TE materials were always kept in contact with the Peltier heater and colder located at the bottom. When the Cu and a-CNT electrodes were alternately contacted with PNP directly from the top direction, the PNP i-TE materials exhibited p-type or n-type behaviors, respectively. As a result, the i-TEG achieves cyclically converting heat to power by alternatively switching a-CNT and Cu electrodes under a constant temperature difference. We believe the proposed work mechanism is more convenient and efficient for practical applications compared to the previously reported methods.
Meanwhile, as the reviewer commented, we have deleted the content "it is impossible to repeatedly turn on/off the heat in the real industry" and further expanded the argument on the advantages of changing electrodes in the introduction part of the manuscript, as followed. "The heat source must be repeatedly established and removed for every charging and discharging cycle to ensure ions move back and forth, which is not convenient in practical applications. Although the i-TE devices periodically contacted the heat and cold source providing another way to convert heat to power, the i-TEGs still need to detach from the heat sources and take time to re-establish the temperature difference in every cycle, which increases energy consumption and reduce the conversion efficiency. Further efforts are needed to address the limitations of ionic thermoelectric technology applications." (Manuscript, Page #3, Line 59). (2) If I am not mistaken the authors observe S = 20 mV/K when using Cu electrodes, and S = -10 mV/K for CNT electrodes. This finding cannot be explained in terms of ionic heats of transport Q+ and Q-, since the latter are material properties, which by definition are independent of the electrodes. The MD simulations suggest that the electrodes modify the ionic probability distribution in a nanoscale surface layer. Since this is the main finding of their paper, the authors should try to explain or at least better characterize experimentally this effect.
Response: This work reported a reversible bipolar thermopower (+20 mV K -1 to -10 mV K -1 ) of the same PNP by testing with Cu and a-CNT electrodes. The MD simulation study found the distribution of TFSI ions near the a-CNT surface is similar to the crystal-like structure (favor TFSIions to diffuse) and a-CNT have stronger interaction with Na + ions (inhibit Na + ions to diffuse), resulting in n-type behavior of a-CNT|PNP|a-CNT. As the reviewer suggested, we further conducted experiments study of the electrode effect on ion distribution by real-time in-situ Raman method, which can dynamically characterize the ions thermodiffusion process under a temperature gradient. And density functional theory (DFT) was conducted to quantitatively investigate the interaction strength between Na + ions, TFSIions and Cu, a-CNT electrodes.
In-situ Raman microspectroscopy is a powerful tool to study the ion transport properties of a material. Especially, the peak location and the intensity of the Raman  Fig. R10. Accordingly, the Raman peak located at ~742 cm -1 related to TFSIanion is selected to investigate the electrode effect on the ion thermodiffusion process of the Cu|PNP|Cu, and a-CNT|PNP|a-CNT system. and e). Interestingly, after the 30s, it's clear to find that the amplitude of the peak intensity of TFSIions significantly decreased until the 160s, which proves that the concentration of TFSIions at PCNT point dropped. As the TFSIions near the hot side interface were motivated by heat, these TFSIions started departing from the hot side to transport to the cold side. Accordingly, the TFSIions diffused away from the hot side toward the cold side and led to a decrease in the concentration of TFSIions near the hot interface after a certain period. The intensity of peak at ~742 cm -1 reached a steady state value of approximately 60% of the initial status. In contrast, for the Cu|PNP|Cu system, the variation of the magnitude of the TFSIpeak intensity at PCu region is very limited (Figs. R12d and e), which is much more weakened than the a-CNT|PNP|a-CNT system. The Raman mapping strongly suggests that the TFSIion is more active near the a-CNT electrode than that of the Cu electrode, demonstrating the a-CNT electrode is more favourable for the diffusion of TFSIions.  Sci. 6, 15, 1996;Phys. Rev. B 54, 11169, 1996;Phys. Rev. B 47, 558, 1993), which the exchange-correlation effects are treated by the generalized gradient approximation (GGA) in the Perdew-Burke-Ernzerhof (PBE) parametrization (Phys. Rev. Lett. 77, 3865, 1996). A vacuum layer > 30 Å is set on the electrode surfaces. The TFSIand Na + ions are separately put on the electrode surface and the structures are optimized. To embody the electronic states of ions, the total valence electronic numbers are set to be Nall-1 for the models with Na + ion and Nall+1 with TFSIion, where Nall indicates the total intrinsic valence electronic numbers as shown in Fig. R13a. In the geometry optimization, cutoff energy of 500 eV, energy convergence of 10 -5 eV, and force convergence of 10 -4 eV/Å are set. The total energy is recorded as Etot,ads. Then, ions moved far away from the electrode by 15 Å, which is enough to exclude the interactions between electrodes and ions, and the total energy is recorded as Etot,far. Lastly, adsorption energy, Ead, can be calculated by Ead= Etot, far -Etot, ads. A higher Ead means a stronger interaction between electrodes and ions.
From the DFT calculation results (Figs. R13b-e), it's interesting to find that the TFSIions formed a stronger interaction with the Cu electrode (0.53 eV) than that of the CNT electrode (0.31 eV). In contrast, the Na + ions formed a stronger interaction with the CNT electrode (1.82 eV) than that of the Cu (1.30 eV) electrode, as summarized in Fig.   R13e, which is consistent with previous MD calculation results.
In summary, the in-situ Raman measurement and DFT results strongly proved that the TFSIions dominated the thermodiffusion process in the a-CNT|PNP|a-CNT system, and the stronger interaction between Na + ions and a-CNT electrode inhibited the diffusion of the Na + ions. As a result, the a-CNT|PNP|a-CNT exhibits the n-type characteristic. 21 We have revised the above discussion in the revised manuscript (Page #9, Line183,  (3) I feel there is a misunderstanding concerning eq. (1) and the subsequent discussion.
In fact, eq. (1) does not give the stationary Seebeck coefficient of iTE materials, but rather the transient ion current after switching on the temperature gradient. Thus eq.
Since "Eq. 1" only describes the ions in transient status for the i-TE materials, it fails to account for the stationary states and doesn't consider the effect of electrodes.
Accordingly, this formula "Eq. 1" is not suitable to explain our experiments. We have deleted the discussion related to "Eq. 1" and cited the reference suggested by the reviewer in the revised manuscript. As the main finding is that bipolar thermopower of the same materials by using different electrodes, the in-situ Raman experimental study together with DFT and MD theoretical analysis results are added to the revised manuscript.
Reviewer #3 (Remarks to the Author): The author used the interaction between ions and electrodes to control the migration of cations and anions by changing the electrode materials, and achieved positive and negative conversion of the thermopower of PNP films. This reversible p-n transition provides a new approach for the construction of thermodiffusion ionic thermoelectric devices. However, this work is incomplete, and there are many 23 issues which should be further clarified. I also have some suggestions for the authors to further polish their paper.
(1). The title of this paper says "ionic thermoelectric polymer composite for continuous energy generation", however, the work on ionic thermoelectric generator is not yet complete. The low power generation of a single PNP film is not meaningful to evaluate its performance. The author needs to connect multiple PNPs in series and consider its stability after many cycles.
Response: As the reviewer suggested, we further investigated the performance of i-TEG by connecting more series of PNP films. As shown in Figs. R14a-c, the i-TEG consists of 10 pairs of Cu electrodes and CNT electrodes connected in series to improve the output power. Firstly, the 10 pairs of the patterned Cu|Cu electrodes were pressed tightly to contact the 10 pieces of PNP films from above (Fig. R14b). After introducing a temperature difference ("T) across 10 pieces of PNP films, taking the data in the first cycle as an example in Fig. 4d, the i-TEG produced a negative thermal voltage Vi until reached a relatively stable value after heating (Fig. R14d). Next, the i-TEG was connected to a load to output power to the external circuit and the voltage Vi dropped to near zero, which was caused by the accumulation of electrons and holes in the electrodes to balance Vi. Then removing the Cu|Cu electrodes while keeping heating constant, the 10 pairs of patterned a-CNT|a-CNT electrodes were switched to contact with the 10 pieces of PNP films (Fig. R14d) and the external resistor was disconnected simultaneously. It is clear to observe the i-TEG produced an opposite sign of thermal voltage (Fig. R14d). Because using a-CNT electrodes make the PNP behave the n-type characteristic and the TFSIanions dominated the thermodiffusion process. Finally, the 24 i-TEG was connected to the load again to output power to the external load.
Furthermore, after repeatedly alternatively switching the patterned a-CNT and Cu electrodes while keeping the heat source constant, the produced thermal voltage of the fabricated i-TEG demonstrated high repeatability after 20 cycles (Fig. R14b).
Importantly, the proposed i-TEG achieves generating cyclic power under a constant heat source without the need to turn on/off the heat source or join/separate materials from the heat source. As a result, there is no necessity to change the thermal contact between the material and heat source and therefore the temperature difference does not need to be re-established, providing a significant innovative impact for expanding the practical applications. Since the cycling stability testing experiments are limited by manual operation, we believe that the cycling stability could be further improved by automatically controlling the processes of exchanging electrodes, which will be investigated in our future work.
We (2). According to Fig. 4, it needs switching the electrodes while also disconnecting the external load and waiting for a certain period to generate the open circuit voltage. I think the generator does not produce power continuously, which is not consistent with the "continuous power generation" claimed in the title of this paper. In addition, there is an error in the labeling sequence of Fig. 4b.

( ) ( )
When started heating, the hot-electrode and cold-electrode sides were connected to the positive and negative electrodes of the voltage meter (Keithley 2182 nano-voltage meter), respectively. The produced voltage difference between the hot side and cold side of Cu|PNP|Cu #VCu (Vhot-Vcold) gave a negative value (Fig. R18a), indicating a higher amount of positive Na + cations moved to the cold side, performing p-type characteristics. Then, the Cu|Cu electrodes were replaced by the a-CNT|a-CNT electrodes, and the connection between a-CNT|PNP|a-CNT systems with voltage meter is exactly the same as the Cu|PNP|Cu systems. The measured #VCNT produced a positive sign (Fig. R18b), implying TFSIanions dominated the thermodiffusion, belonging to the n-type characteristic. By fitting the slope of the "-"VCu vs "T" or "-"VCNT vs "T", the measured thermopower of Cu|PNP|Cu and a-CNT|PNP|a-CNT are 20 mV K -1 and -10.64 mV K -1 , respectively. We found the coordinate in the Y-axis should be "-"V" instead of ""V", which is revised accordingly as shown in Figs. R18 c-d.
We have added the detail of the measurement setup and corrected the typo marked with red color in the manuscript and the Supplementary Information (Pages #S4 and #S26, Fig. S1). (4) What are the advantages of VA-CNT as electrodes compared to other carbon materials such as SWCNT or MWCNT? The reason for choosing VA-CNT arrays as electrodes should be described.
Response: As suggested by the reviewer, the physical properties of aligned CNT were further described. To avoid misunderstanding, we have changed the name "vertical aligned CNT" to "aligned CNT (a-CNT)" in the revised manuscripts. As the aligned CNT films were placed horizontally, and the length direction of the aligned CNT was parallel to the i-TE polymer material when performing test, which is not vertical to the polymer material.
Advantages: Firstly, the aligned CNT thin film is commercially available with good quality control and consistency, excellent property repeatability and stability (Nanjing Ji Cang Nano Technology Co., Ltd. (Nanjing, China), and the product number is JCNTF-20C). Meanwhile, the aligned CNTs consist of bundles of carbon tubes arranged orderly along the length direction with small entanglements, they exhibited higher conductivity of 3×10 5 S m -1 , a lower sheet resistance of 1~1.5 $ m -2 , excellent flexibility, low cost, and stronger mechanical strength of ~120 MPa compared to common SWCNT and MWCNT-based films, as summarized in Table R1. Moreover, due to the softness and self-adhesive nature of the aligned CNT, it is easy to form tight contact with the PNP composite compared to thick SWCNTs and MWCNTs films.
Having good contact is of great significance for reducing contact resistance and improving the overall ionic thermoelectric conversion performance. Compared to the thermoelectric property of PNP tested with the MWCNT and SWCNT electrodes, the a-CNT|PNP|a-CNT performed higher thermopower of -10.2±0.83 mV K -1 than SWCNT|PNP|SWCNT (-5.2±1.35 mV K -1 ) and MWCNTs (-8.17±1.2 mV K -1 ).
We have added the discussion of the advantages of aligned CNTs as the electrodes marked with red color in the revised manuscript (Page #7, Line 139) and Supplementary Information (Page #S8, Fig. S5, Table S1).

Table R1
The comparison of the physical property of the three CNTs.  aligned CNT electrode surface at 300K.
(6). The ionic thermoelectric polymer was described as all-solid-state i-TE material.
However, this i-TE material contains liquid propylene carbonate (PC), so it is not